设置对象属性（如果Javascript中为真）

Question

I want to transfer properties from objA to objB while changing their names and overriding only if they are truthy . Using lodash but an ES6 solution would be even better.

This is what I have so far:

// My initial objects
const objA = {a: 1, b: '', c: null};
const objB = {x: 7, y: 8, z: 9};

// Extracting and renaming
let {x: a, y: b, z: c} = obj1;

// Sanitizing
const temp = _.pickBy({x, y, z}, _.identity);

// Merging A and B
return {...objB, ...objA}; // {x: 1, y: 8, z: 9}

Is there a less contrived way of doing this?

Answer 1

Both solution use a Map to rename array keys, and Object#assign to merge objects (the snippets don't support object rest/spread).

ES2017

Use Object#entries (ES2017) to get the keys and values of objA , rename and add them only if the value is not falsy.

 const a2x = new Map([['a', 'x'], ['b', 'y'], ['c', 'z']]); const objA = {a: 1, b: '', c: null}; const objB = {x: 7, y: 8, z: 9}; const result = Object.assign({}, objB, Object.entries(objA).reduce((r, [k, v]) => v ? Object.assign(r, { [a2x.get(k)]: v }) : r, {})); console.log(result); 

lodash:

Use _.mapKeys() to change the names of the keys, then _.pickBy() with _.identity() to remove falsy values.

 const a2x = new Map([['a', 'x'], ['b', 'y'], ['c', 'z']]); const objA = {a: 1, b: '', c: null}; const objB = {x: 7, y: 8, z: 9}; const result = Object.assign({}, objB, _.pickBy(_.mapKeys(objA, (v, k) => a2x.get(k)), _.identity)); console.log(result); 

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